I just picked up a Coghlan's Flint Wheel to test. It was a total bust for me! It's about 5 inches long by 1 inch wide, which was the only good thing about it. I initially thought it would be great because it IS large, as I had trouble in the past holding the tiny Spark-Lite from Four Seasons Survival, which comes with Tinder Quik plugs. And it's definitely much easier to hold than the Spark-Lite, but I found the spark wheel very hard to turn. It puts out good sparks, but if my fingers were...
Coghlan's Flint Wheel and Coghlan's Emergency Tinder
Coghlan's Flint Wheel and Coghlan's Emergency Tinder